POLIO AETUS ICHTHYAETTTS. 73 



and bluish fleshy at gape ; cere above leaden, at lower edge bluish ; legs and feet fleshy white, with a bluish tinge ; 

 claws black. 

 Entire head, upper part of hind neck, and throat cinereous ashy, the crown and nape shaded with brown ; back, rump, 

 scapulars, and wings dark wood-brown, passing on the interscapular region into a paler shade, which blends above 

 into the grey of the neck ; in old birds the latter part is especially pale, and sometimes has the feathers edged 

 light ; primaries dull black ; secondaries blackish brown, the inner webs somewhat cinereous ; chest, breast, and 

 upper flanks light wood-brown, blending into the grey of the throat ; abdomen, lower flanks, thighs, under tail- 

 coverts, and tail white, terminal portion (from 1J to 2 J inches) of tail black; lesser under wing-coverts umber- 

 brown. When freshly acquired, the hues of the upper surface are much darker than when the bird is in old- 

 feather, in which state the breast fades considerably, becoming a light chocolate-brown. The chin is whitish in 

 some birds, probably those which have for the first time acquired the adult plumage. 



Young. In the bird of the year the iris is hazel-brown ; bill and legs much as in the adult. 



The nestling is covered with white down. 



On becoming fully plumaged at about four months' old, the upper part of the forehead, crown, hind neck, and inter- 

 scapular region are light chocolate-brown, deepening slightly on the scapulars, back, and wing-coverts ; edge of 

 forehead, throat, face, and above the eye, together with the tips and centres of the head and hind-neck feathers, 

 and the tips only of those of the lower part of the neck, bufly white ; tips of the back, scapulars, and wing-covert 

 feathers fulvous-grey, passing with a tawny hue into the brown ; quills blackish brown, all but the longer primaries 

 and the secondaries tipped with the fulvous hue ; the primaries, secondaries, and greater wing-coverts crossed on their 

 inner webs with light bars, paling into whitish at the inner edges ; tail brown, tipped with fulvous, paling beneath 

 the coverts into whitish, and mottled, except on the bars, with fulvous ; a broad, blackish, terminal band, preceded 

 by a narrow undefined bar of the same, on the central feathers only. 



Lower part of fore neck, chest, flanks, and breast more or less pale tan-brown, with shaft-stripes and tips of fulvous- 

 grey, which are usually broadest on the chest ; bases of the chest-feathers dark brown ; abdomen and thigh-covert 

 feathers white, mottled at the tips and terminal margins with the pale hue of the lower breast ; under tail-coverts 

 faintly washed with the same ; under surface of tail at its base white, mottled towards the terminal band with grey ; 

 lesser under wing-coverts light tawny fulvous ; greater series white, barred with black ; axillaries pale tawny, 

 marked across the centres of the feathers with brown and white. 



At the end of the first year the plumage fades, sometimes to an extraordinary degree, the chest and breast becoming 

 whitish, merely washed about the margins of the feathers with very pale tawny grey ; on lifting up the feathers 

 of the chest the brown bases are found in their original state ; the upper surface does not undergo such a change, 

 except that the light tippings, by reason of abrasion, are less conspicuous ; the tail, however, becomes considerably 

 paler than in the freshly-plumaged yearling. The adult plumage, as far as I can ascertain, is not put on until 

 after the second moult. 



Obs. In my notes on " Ceylonese Ornithology and Oology" (loc. cit.) I pointed out that Ceylon examples of this Eish- 

 Eagle were, as a constant rule, smaller than those from other places. An examination of specimens in the 

 National collection from the Malay region, and a perusal of the dimensions given of late in various articles in 

 ' Stray Eeathers,' confirms the opinion that our bird constitutes a small race of P. iehihyaetus of Java. This latter 

 is not invariably a larger bird than the Ceylonese, as I have examined a specimen from Sumatra with a wing of 

 17 - 7 inches, and that of another collected by Mr. Armstrong in the Eangoon district measures only 18-2 ; on the 

 other hand the type specimen from Java in the British Museum measures 2O0, and an immature bird, presumably 

 a female, so young that it could not be sexed, shot by Mr. Oates in Burmah, had the wing as large as 19 - 0, both 

 of which latter dimensions I have never known attained to in the Ceylon bird. The Javan bird has a less cinereous 

 brown hue, both above and beneath, than several that I have examined from other places ; but this is a worthless 

 character, as the brown tints are variable in the Ceylon bird, depending entirely on the age of the feather. 



As regards the position of this Eagle among its congeners, I have not placed it with the Ospreys, as Mr. Sharpe has 

 done in his ' Catalogue,' but kept it in its hitherto accepted position among the Sea-Eagles. It differs structurally 

 from the Osprey in having two foramina in the sternum, the posterior edge of which is devoid of the tolerably 

 deep notches existing in that of Pandion, and in not having the keel, which is also much shallower, prolonged 

 to the edge ; the sternum is likewise weak, narrow, and more angulated than in the Osprey ; the feathers do not 

 want the accessory plumule, and the bony protection or brow above the eye, which does not exist in the Osprey, 

 is present in this genus as in all other Eaptors. In the structure of the foot, the outer toe of which is partially 

 reversible, and also in the rounded claws, Polioaetus has some affinities with Pandion ; but it differs again in its 

 much shorter wings and the habits consequent on this structure. 



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